Standardization works of international mobile telecommunication (IMT)-advanced which is a next generation (i.e., post 3rd generation) mobile communication system are carried out in the international telecommunication union radio communication sector (ITU-R). The IMT-advanced aims at support of an Internet protocol (IP)-based multimedia service with a data transfer rate of 1 Gbps in a stationary or slowly moving state or 100 Mbps in a fast moving state.
3rd generation partnership project (3GPP) prepares a system standard satisfying requirements of the IMT-advanced, that is LTE-advanced, which is an improved version of long term evolution (LTE) based on orthogonal frequency division multiple access (OFDMA)/single carrier-frequency division multiple access (SC-FDMA) transmission. The LTE-advanced is one of promising candidates for the IMT-advanced. A relay station technology is one of main technologies for the LTE-advanced.
A relay station (RS) is a device for relaying a signal between a base station (BS) and a user equipment (UE), and is used for cell coverage extension and throughput enhancement of a wireless communication system.
In the wireless communication system employing the RS, a frequency band at which the RS transmits a signal to the BS may be equal to a frequency band at which a UE (e.g., a relay UE) connected to the RS transmits a signal to the RS. In this case, if a time duration in which the RS transmits a signal to the BS coincides with a time duration in which the relay UE transmits a signal to the RS, it is difficult for the RS to receive a signal from the relay UE due to self interference.
Uplink control information can be included in a signal transmitted by the relay UE. Examples of the uplink control information include a scheduling request (SR), a hybrid automatic repeat request (HARQ) acknowledgement (ACK)/non-acknowledgement (NACK) for previously performed downlink transmission, channel information that is fed back for previously performed downlink transmission, a reference signal for scheduling uplink transmission, etc. The uplink control information is transmitted either periodically or aperiodically, and can be transmitted by using a time, radio resource, and transmission format indicated by a higher layer signal.
However, when the time duration in which the RS transmits the signal to the BS overlaps with the time duration in which the relay UE transmits the signal to the RS as described above, the RS is unable to receive the uplink control information, and as a result, the BS is unable to know the uplink control information transmitted by the UE. As a result, the wireless communication system employing the RS may experience performance deterioration.